Get Your Body Fat Estimate With Just a Tape Measure
Take a few simple measurements and see your estimated body fat, where it falls on the scale, and how your weight splits between fat and lean mass.
This tool was built by Serge (MSc) using the US Navy circumference method, a well-known formula based on height, neck, waist, and hip measurements. My background is a lifelong natural lifter with over a decade of drug-free training and a science background (MSc).
My tools are for educational purposes and give practical guidance, not professional advice.
Bathroom scales tell you how heavy you are, not what that weight is made of. Two people at the same weight can look and perform very differently, and body fat is the number that explains why.
You do not need a clinic or special equipment. A soft tape measure and a few minutes are enough for a useful estimate you can repeat as often as you like.
Why I Prefer a Tape Measure
When I want a quick read on body composition, a tape measure is what I would use. It costs almost nothing, it works anywhere, and I can repeat it exactly the same way every time.
That repeatability is why I recommend it. A single number matters less than the direction it moves over a few months, and a tape measure shows that direction clearly.
Taking the Measurements Properly
Measure the neck just below the larynx, with the tape sloping slightly down toward the front. Measure the waist at the level of your navel for men, or at the narrowest point for women, relaxed and without pulling your stomach in. Women also measure the hips at their widest point.
Stand tall, keep the tape snug but not tight, and read it at the end of a normal breath out. Take each measurement twice, and if the two readings differ, use the average.
How Accurate Is This?
It is an estimate, and it can be off by a few percentage points either way. Very muscular people may see a slightly higher figure than reality, while people with an unusual build can see the opposite.
So use the result as a reference point, not a verdict. Measure again every four weeks at the same time of day, and judge yourself by the trend.
What to Do With Your Number
If you entered your weight, the lean mass shown is a good input for the FFMI calculator, which shows how your muscle compares with typical natural levels.
If you want to lower your body fat at a sensible pace, the calorie deficit calculator turns a goal weight and date into a daily calorie target. To make sure you eat enough protein while you do it, check the protein intake calculator.